implemented internal file sharing and saving, added server-side file references, refactored share pickers for unified flows, and updated UI branding labels

lib/widget/file_viewer.dart

@@ -11,6 +11,7 @@ import 'package:share_plus/share_plus.dart';
 import 'package:syncfusion_flutter_pdfviewer/pdfviewer.dart';
 
 import '../routing/app_routes.dart';
+import '../share_intent/remote_file_ref.dart';
 import '../state/app/modules/settings/bloc/settings_cubit.dart';
 import 'info_dialog.dart';
 import 'placeholder_view.dart';
@@ -19,13 +20,24 @@ import 'share_position_origin.dart';
 class FileViewer extends StatefulWidget {
   final String path;
   final bool openExternal;
-  const FileViewer({super.key, required this.path, this.openExternal = false});
+
+  /// When set, enables the in-app actions "An Chat senden" and "In Dateien
+  /// speichern" — these need a server-side reference, not the local cache
+  /// path. Aufrufer reichen die Referenz durch (siehe AppRoutes.openFileViewer).
+  final RemoteFileRef? remoteFile;
+
+  const FileViewer({
+    super.key,
+    required this.path,
+    this.openExternal = false,
+    this.remoteFile,
+  });
 
   @override
   State<FileViewer> createState() => _FileViewerState();
 }
 
-enum FileViewingActions { openExternal, share, save }
+enum FileViewingActions { openExternal, share, save, sendToChat, saveToCloud }
 
 /// Workaround for a Syncfusion PDF viewer race: SfPdfViewer's internal
 /// LayoutBuilder calls `localToGlobal` during build, which asserts when an
@@ -110,6 +122,16 @@ class _FileViewerState extends State<FileViewer> {
                   context,
                   widget.path,
                   openExternal: true,
+                  remoteFile: widget.remoteFile,
+                );
+                break;
+              case FileViewingActions.sendToChat:
+                AppRoutes.openInternalShareToChat(context, widget.remoteFile!);
+                break;
+              case FileViewingActions.saveToCloud:
+                AppRoutes.openInternalSaveToFolder(
+                  context,
+                  widget.remoteFile!,
                 );
                 break;
               case FileViewingActions.share:
@@ -154,6 +176,24 @@ class _FileViewerState extends State<FileViewer> {
                 dense: true,
               ),
             ),
+            if (widget.remoteFile != null) ...[
+              const PopupMenuItem(
+                value: FileViewingActions.sendToChat,
+                child: ListTile(
+                  leading: Icon(Icons.chat_bubble_outline),
+                  title: Text('An Talk-Chat senden'),
+                  dense: true,
+                ),
+              ),
+              const PopupMenuItem(
+                value: FileViewingActions.saveToCloud,
+                child: ListTile(
+                  leading: Icon(Icons.cloud_outlined),
+                  title: Text('In Cloud speichern'),
+                  dense: true,
+                ),
+              ),
+            ],
             const PopupMenuItem(
               value: FileViewingActions.share,
               child: ListTile(